The present invention relates in general to a pneumatic starter arrangement for an internal combustion engine, and in particular to an arrangement of the kind which includes a pneumatic starter motor, a gear train including an axially retrievable pinion for transmitting rotary movement of the starter motor to the internal combustion engine, a pneumatic actuator having a piston coupled to the pinion for controlling the axial movement of the latter, a source of pressure air, a first conduit connecting the pressure air source to the actuator, a second conduit connecting the pressure air source to the starter motor, a main control valve in the second conduit, a pilot valve in the first conduit and a bypass conduit connecting the starter motor to the actuator.
A pneumatic starter arrangement of this kind is known from the German Pat. No. 3,020,930 and its advantageous quality has been already proven in practice. On the other hand, however, it has been also found in practice that in the automatic course of the starting process meshing errors still may occur. This happens for example in the case when the starting process is incorporated in a chain of automatically running, preprogrammed processes. The enforced functions following in an automatic operation require therefore in absolutely reliable and flawless operational conditions which however cannot be met in the starting process.
Meshing errors, for example can occur in the case when the teeth of the starter pinion and/or of the flywheel of the internal combustion engine to be started are damaged and the starter pinion is clamped in the teeth of the flywheel.
It may also happen during the starting operation that during the engagement of the starter pinion with the teeth of the flywheel the beveled leading edges of the teeth of the starter pinion when considered in the rotational direction of the latter, and the trailing edges of the teeth of the flywheel abut against each other and consequently inspite of relatively small bevel of the starter pinion and flywheel gears, the latter may become clamped one with the other.